356 HOWARD AYERS 
fore held to be formed by branches from left nerves only, shows 
that we have yet to learn the complete story of the innervation 
of the jaw apparatus. Even though van Wijhi’s explanation 
of the asymmetry of the formation of the inner buccal plexus 
and the innervation of the velum is largely correct, the fact 
remains that the right side can and does supply its bilateral 
share to the buccal nerve supply of the inner plexus occasionally 
to show jaw apparatus. The remnant of the distal part of the jaw bar is attached 
to the hyoid as in Bdellostoma and runs forward and upward to the tentacular 
cartilages of the nasal region, thus preserving the ancient amphioxine jaw bar in 
a Gnathostome head. 
if not frequently, and it would not require much more than has 
actually been observed to establish the complete bilateral sym- 
metry in the descendants of Amphioxus which we observe in the 
higher forms, where the nerve supply of the right and left sides 
is usually finely balanced. 
Thus the five nerve trunks innervating the jaw apparatus 
run ventrolaterad with a slight inclination cephalad. In the 
jaw their main branches run longitudinally. They leave the 
central nerve cord as separate and distinct dorsal roots. There 
